Thermostatic structure



Oct. 15, 1935. R. E. NEWELL THERMOSTATIC STRUCTURE Filed Jan. 28, 1935Patented Uct. iii, 1935 UNITED STATES PATENT OFFICE THERMOSTATICSTRUCTURE Application January 28, 1935, Serial No. 3,885

5 Claims.

This invention relates to thermostatic structures for the operation ofcontrol devices such as valves, switches, or the like, in various typesoi. systems. a.

In my United States Patent No. 2,000,294 dated May 7, 1935, is describeda thermostatic structure for operating valves, switches, or the like,and comprising essentially a support, an element having a return bendintermediate the ends thereof and having oppositely disposed armportions extending from said bend, one of said arms being rigidlysecured to said support, and, adjacent said return bend, a cross bridgeextending between and rigidly secured to the arms of said element andarranged to move one of said arms relative to the other as a result ofany difference in the temperature of the return bend and that of thecross bridge.

In the preferred structure of the above mentioned patent, the arms 01the U-shaped element are adapted to extend through holes in thecrossbridge, the arms being swaged to hold the crossbridge in placeadjacent the return bend 0! said U-shaped member. In the manufacture ofsuch a device, it was found desirable to change said holes to slots totake care of any slight variations in form that might occur in shapingthe U-shaped member. After positioning the cross-bridge on said U-shapedmember, the edges of said slots were pressed around the arms of saidmember to rigidly secure the cross-bridge to both arms.-

It is necessary to anneal the assembled structure in order to remove anystresses set up in the metal by the bending or shaping of the members.Otherwise, the completed unit will not remain stable in its positionrelative to the control member to be operated. In the annealing processthe cross-bridge and the arms of the U-shaped member change slightlytheir position with respect to each other and thus tend to loosen thecross bridge which is secured to said arms. This creates difliculties inthe manufacture of a standard product.

When thermostatic expansion and movement takes place in such astructure, the cross-bridge, being rigidly secured to both arms, mustnecessarily flex slightly because of the spreading of said arms. Thisflexing, of course, consumes a portion of the power developed by thestructure.

By my present invention, I provide an improved thermostatic structurewhich overcomes the aforementioned d'ifliculties, and presents new andoriginal features through which greater power, efficiency, and quickeraction, as well as uniformity and lower cost, may be obtained when thearticle is manufactured in quantities.

In the accompanying drawing, I have shown my invention as embodied in astructure particularly adapted to be used in connection with s a pilotflame safety valve or switch. However, it is not necessarily limited tosuch structures. As will be explained later, the device may also be usedas a regulation thermostat to control the temperatures to which it issubjected. 10

In the drawing-- Figure 1 is an elevation view of a preferred form ofthe present unit conveniently mounted and arranged to actuate a controlmember in accordance with temperatures created by a pilot l6 flame;

Figure 2 is an elevational view of the structure dissociated fromsupporting means and the pilot li Figures 3 and 4 are side elevations ofstructure 20 shown in Figure 2;

Figures 5 and 6 are detail views of the new adjustable cross-piece; and

Figure 7 shows my invention as embodied in a structure similar to thatof Figure 1 but having 5 a modified form or cross-piece and another formof burner particularly designed to act as a pilot in connection withthis device.

As shown in Figures 1 to 6, inclusive, the member I has a flexiblereturn bend 2 with arms! 3' and 4 extending therefrom. The arm 3 islonger than arm 4 and has its end portion 5 shaped' and adapted to beconveniently attached to support 6 by screw threads and held in place bylock nut I. This adaptation of the end portion 5 oi. as the longer arm 3merely eliminates the necessity of a bracket or similar support.

The shorter arm 4 is allowed to remain free of the support and may be ofany desired length to obtain sufiicient amplification of movement. 0 Anadjustable actuating pin 8 is inserted in the end of arm 4, andcooperates with a rod 9 or any other suitable means provided to operatethe control to which the device may be attached. The slit I0 is designedso that a blow of a hammer, or the like, on the end 01 arm 4will tightenthe threads about the adjustable actuating pin 0, thus looking itagainst accidental displacement.

Mounted on the end portion 5 oi. arm 3, and extending through hole lltherein, is a burner I2, positioned to direct the flame l3 upon athermally responsive cross-piece it, one end of which abuts against thearm 4, while the other end extends through and is adjustably secured tothe opposite arm 3 by screw threads l5 and lock nut l0. Properadjustment of the cross-piece II is facilitated by screw-driver slot II.

In assembling, the bent member is first annealed to relieve the strainsincidental to shaping. The cross-piece is inserted and adjusted so thatthe end opposite the threaded portion abuts against the shorter arm ofthe member and the cross-piece is then locked in place. The end portionof the longer arm of the bent member is attached to the support and theactuating pin placed in the end of the free arm and operativelyconnected with the control member, and adjusted until the desiredtemperature range is obtained. The structure is then ready for use.

The flame i3, impinging on the cross-piece i4, causes it to expand andmove the free arm 4 to a position such as shown by dotted lines inFigure 2. Such movement is amplified by the length of said arm 4, theend of which actuates the bar I which in turn operates a suitablecontrol. When the flame is removed, the cross-piece cools and contracts.Since all strains have previously been removed from the member I byannealing and since the movement of said free arm is extremely smallwhen compared to the size of said member I, the natural resiliency ofthe metal of which said member is formed causes it to return to itsoriginal position.

The member i may be formed of a flat strip of suitable material, thestrip being wide enough so that the member is more or less rigid exceptfor the portion forming the flexible return bend, which portion isnarrowed or otherwise reduced in size to permit flexing. The member mustalso be large enough and formed of material having sumcient strength tooperate properly the control means for which it is designed, withouttaking a set.

The cross-piece may be located at any desired point on the member I.However, I have found the most desirable position is one in which thecross-piece is adjacent the flexible return bend of said member, asshown in Figure 1, as this gives the free arm maximum movementamplification. This cross-piece should be only large enough to havesuflicient strength to carry the load imposed upon it at the highesttemperature to which the device is subjected. Such a cross-piece is thensmall enough to reach maximum temperature quickly and to cool rapidlywhen the flame is removed therefrom.

It is easily seen that by merely providing a cross-piece of a materialhaving a considerably higher coefllcient of expansion than that of themember I, this structure can be used successfully as an ordinarythermostat for accurate temperature control or regulation. One of theadvantages of an adjustable cross-piece of the type described is that itmay be quickly and easily removed and another cross-piece, which mayhave a different coefllcient of expansion, readily inserted. This rapidconversion from one type of thermostat to another naturally increasesthe value of the structure, especially from a manufacturing standpoint.

In Figure 7, I have shown a structure, somewhat similar to that ofFigure 1, in which a member ll has a flexible return bend I! with armsand II extending therefrom, arm 20 being attached to a support I! andarm 2| being free of said support and operatively engaged by means ofpin 23 with any suitable control operating means such as rod 24. Thethermally responsive cross-piece II has one end securely fastened to armIII and extends therefrom to the other arm and abuts against the end ofscrew 26. This screw 26 is adjustably supported by arm 2| and is lockedin place by nut 21 and serves as an adjustable bearing contact point forthe arm 2|.

The runner burn-er 28 is supported substantially parallel to thecross-piece by any convenient method (not shown). The burner tubeextends through hole 29 in arm 2i but not touching said arm and thencethrough hole 30 in arm 20, the burner jets of the runner being arrangedso that a series oi small flames 3| impinges on the crosspiece 25 and atleast one flame 32 burns outside of the structure and thus presents aconvenient method of lighting a main burner 33.

This type of pilot burner is particularly advantageous for installationsin which it is impossible to locate the structure close enough to themain burner so that a pilot burner as shown in Figure 1 would ignitesaid main burner. It is to be noted that either type of burner may beused with either design of cross-piece, thus both the member I ofFigures 1 through 4 and the member l8 of Figure 7 contain openingssuitable for the use of either type of burner.

The structure shown in Figure 7 operates in a manner similar to that ofthe device of Figure l. The flames 3| impinging upon the cross-piece 25cause it to expand and move arm 2| which actuates control member 24. isextinguished it is reignited by the other flames of the runner. If, forany reason, the entire pilot runner is extinguished, the cross-piecewill cool, contract, and allow arm ii to return to its originalposition.

The advantages of making the cross-piece as described in thisspecification are quite clear and distinct, especially from themanufacturer's viewpoint. Any small errors in the forming of the bentmember or slight changes of shape in the annealing of said member areeasily taken care of by the adjustable feature. Loss of power caused bythe necessity of flexing a bridge rigidly secured to both arms of saidmember is eliminated, thereby the efliciency of the structure isincreased.

In case one jet flame One arm of said member having a free pivotal 5contact with the end of said cross-piece, rather than being rigidlysecured thereto, permits a more uniform action. With this increasedfreedom of movement, and the additional power available. the deviceoperates in approximately one-half of the time required by the one shownin my aforementioned copending application. The crosspiece of thepreferred design allows rapid and easy removal and replacement of saidcross-piece if desired, and the simplicity of forming and assembling theparts materially reduces manufacturing costs.

Though I have shown and described a preferred embodiment and amodification of my invention, I do not intend to be limited thereby, asmy invention may be otherwise embodied within the scope of the appendedclaims.

I claim:

1. A thermostatic structure having, in combination, a support, a memberhaving a flexible return bend with arms extending therefrom, one of saidarms being fastened to said support, a thermally-responsive cross-piecesecured to one of said arms and in free bearing connection with theother arm, whereby thermostatic expansion or contraction of saidcross-piece will result in a sensitive flexing of said bend and movementof the free arm of said member, and means for adjusting said freebearing connection.

2. A thermostatic structure having, in combination, a support, a memberhaving a flexible return bend with arms extending therefrom, one of saidarms being fastened to said support, a thermally-responsive cross-piecesecured to one of said arms and operatively engaged, by free bearingcontact, with the other arm so that thermostatic expansion orcontraction of said cross-piece will result in a sensitive flexing ofsaid bend and movement of the free arm of said member, and screw meansfor adjusting said free bearing contact.

3. In a thermal control system, the combination of a member having aflexible return bend with arms extending therefrom, means connected withone of said arms for supporting said member, a thermally-responsivecross-piece extending from one of said arms to the other and havinadjusting means cooperating therewith for obtaining operative engagementof said cross-piece with said arms, whereby a sensitive flexing of saidbend and movement of the arm that is free of said supporting means willresult from thermostatic expansion or contraction of said cross-piece,and a control member operatively connected with said movable arm.

4. In a thermal control system, the combination of a support, a memberhaving a flexible return bend with arms extending therefrom, one of saidarms being fastened to said support and the other arm operativelyengaged with a control member, and a thermally-responsive cross-piecesecured to one of said arms and in free bearing connection with theother arm, whereby thermostatic expansion or contraction of saidcrosspiece will result in a flexing of said bend and movement of the armwhich is operatively engaged with aforesaid control member.

5. In a thermal control system, the combination of a support, a memberhaving a flexible return bend with arms extending therefrom, one of saidarms being fastened to said support, a thermally-responsive cross-piecesecured to one of said arms and operatively engaged, by free bearingcontact, with the other arm so that thermostatic expansion orcontraction of said cross-piece will result in a sensitive flexing ofsaid bend and movement of the arm that is free of said support, acontrol member connected to said movable arm, and means for adjustingsaid free bearing contact.

ROBERT E. NEWELL.

